Power switch

ABSTRACT

A power switch is for interrupting an electrical circuit when current and/or current time span threshold values are exceeded. The power switch includes an energy converter, which on the primary side is connected to the electrical circuit, and on the secondary side provides an energy supply for at least one control unit of the power switch. The energy converter has a core having a remanence flux density (Br2) of less than 30% of the saturation flux density (Bs2) or a coercive field strength (Hc2) of less than 10 A/m.

Priority Statement

This application is the national phase under 35 U.S.C. § 371 of PCTInternational Application No. PCT/EP2017/078683 which has anInternational filing date of Nov. 9, 2017, which designated the UnitedStates of America and which claims priority to German patent applicationnumber DE 102017201239.0 filed Jan. 26, 2017, the entire contents ofwhich are hereby incorporated herein by reference.

FIELD

Embodiments of the invention relate to a circuit breaker.

BACKGROUND

Circuit breakers are protective devices which function in a similarmanner to a fuse. Circuit breakers monitor the current flowing throughthem via a conductor and interrupt the electrical current or energy flowto an energy sink or a load, which is referred to as tripping, ifprotective parameters such as current limit values or current periodlimit values, that is to say if a current value is present for a certainperiod, are exceeded. The interruption is effected, for example, by wayof contacts of the circuit breaker which are opened.

There are different types of circuit breakers, in particular forlow-voltage circuits or networks, depending on the level of theelectrical current provided in the electrical circuit. In the sense ofthe invention, circuit breaker is used to mean, in particular, switcheswhich are used in low-voltage installations for currents of 63 to 6300amperes. More specifically, closed circuit breakers are used forcurrents of 63 to 1600 amperes, in particular of 125 to 630 or 1200amperes. Open circuit breakers are used, in particular, for currents of630 to 6300 amperes, more specifically of 1200 to 6300 amperes.

Open circuit breakers are also referred to as air circuit breakers, ACBfor short, and closed circuit breakers are referred to as molded casecircuit breakers, MCCB for short.

Low voltage is used to mean, in particular, voltages up to 1000 volts ACor 1500 volts DC.

In the sense of embodiments of the invention, circuit breaker is used tomean, in particular, circuit breakers having a control unit such as anelectronic trip unit, ETU for short. The control unit monitors the levelof the electrical current measured by sensors such as Rogowski coils andadditionally the voltage or/and other parameters of the electricalcircuit in a similar manner and interrupts the electrical circuit.Electrical energy is needed to operate the control unit and is providedby an energy converter, for example a transformer. The latter isconnected, on the primary side, to the electrical circuit to beprotected and, on the secondary side, to the control unit.

In the event of an excessively “high” current flow, circuit breakersinterrupt the circuit according to their protective parameters orresponse values. The protective parameters or response values aresubstantially the level of the current and the time after which thecircuit is intended to be interrupted in the case of a persistently“high” current flow. In contrast to a fuse, these protective parametersor response values are adjustable in a circuit breaker, for example viathe control unit such as an electronic trip unit.

The energy converters are used for the so-called energy self-supply ofcircuit breakers. They are based on the principle of magneticallycoupled power transmission, as a result of which energy is provided forthe control unit such as an electronic trip unit.

Energy converters such as current converters which operate in the linearrange up to approximately 200% of the defined primary current arecurrently used in circuit breakers.

The currently used energy converters such as current converters arebased on a wound core made of grain-oriented FeSi magnetic sheet steel(ferrosilicon). This material has a high permeability along the rollingdirection, a high saturation magnetization of typically 1.9 T and arelatively low magnetic power loss of typically approximately 1-2 W/kgat 50 Hz. These parameters enable a very low magnetic cross section andtherefore a very compact design of the current converter in order toachieve the minimum required secondary output power.

EP 0 563 606 A2 discloses a current converter forpulse-current-sensitive residual current circuit breakers. Furthermore,EP 2 416 329 A1 discloses a magnet core for low-frequency applicationsand a method for producing it. DE 10 2013 211 811 A1 furthermorediscloses a converter unit. Finally, EP 1 154 539 A1 discloses aresidual current circuit breaker with a summation current converter.

SUMMARY

At least one embodiment of the present invention is directed toimproving a circuit breaker.

In particular, at least one embodiment of the application is directed toa A circuit breaker for interrupting an electrical circuit upon at leastone of current and current period limit values being exceeded,comprising:

-   -   an energy converter, connected on a primary side to the        electrical circuit and, connected on a secondary side, to        provide an energy supply for at least one control unit of the        circuit breaker, the energy converter including a core, a        remanence flux density of the core being less than 30% of a        saturation flux density of the core, wherein the core includes a        ferromagnetic nanocrystalline material.

BRIEF DESCRIPTION OF THE DRAWINGS

The described properties, features and advantages of this invention andthe manner in which they are achieved become more clearly and distinctlycomprehensible in connection with the following description of theexemplary embodiments which are explained in more detail in connectionwith the drawings.

In this case, in the drawings:

FIG. 1 shows a first graph having a first hysteresis curve,

FIG. 2 shows a second graph having a second hysteresis curve,

FIG. 3 shows a cross section through a converter unit having a particlelayer above an upper secondary winding,

FIG. 4 shows the converter unit according to FIG. 3 with a film abovethe upper secondary winding,

FIG. 5 shows the converter unit according to FIG. 4 with a perforateddisk element resting on the film.

DETAILED DESCRIPTION OF THE EXAMPLE EMBODIMENTS

In particular, at least one embodiment of the application is directed toa circuit breaker having an energy converter including a core, theremanence flux density (Br2) of which is less than 30%, in particularless than 20%, of the saturation flux density (Bs2).

Furthermore, its coercive field strength (Hc2) may be less than 10 A/m,in particular less than 5 A/m.

This core is made of a ferromagnetic nanocrystalline material.Nanocrystalline material is used to mean a material having a particlesize of 1 to 100 nm, in particular a material having a particle size of5 to 20 nm. Grain sizes of 10 nm are particularly suitable, inparticular.

This has the advantage that the typical Z shape of the magnetichysteresis loop in the known grain-oriented FeSi magnetic sheet steel orelectrical steel, see FIG. 1, is avoided. In the case of theconventional FeSi material (ferrosilicon), the energy converters exhibita remnant magnetic flux without an external magnetic field. Thisso-called remanence effect is particularly great if the magnetic coreenters the state of magnetic saturation as a result of the load of acontrol unit such as an electronic trip unit (ETU). This state isreached if a very high secondary current is caused by a very highprimary current, the secondary power increases and the apparent power ofthe current converter is consequently exceeded.

In the state of magnetic saturation, the magnetic flux in the core canno longer change over time. This results in no secondary voltage beinginduced and in the secondary current collapsing. The described behavioris often observed in the event of a short circuit in the electricalcircuit, as a result of which the primary-side current in the energyconverter is very high.

The state of high remnant magnetization is canceled by the subsequentpolarity change in the primary current. However, the task of the controlunit such as the electronic trip unit in the circuit breaker is todetect the short-circuit situation and to trip the switch in order toprevent the further primary-side current flow through an open switch.This is then possibly carried out only with a delay.

If the switch is switched on again at a later time, the polarity of theprimary current flowing again cannot be predicted. It may thereforehappen that the polarity is the same as the last polarity beforetripping and the electronic operational readiness is thus delayed by apolarity change. This situation is particularly critical in single-phasesystems since the delay may last for up to half a period.

Remnant magnetization is an intrinsic property of conventional magneticsheet steel with high permeability. This occurs both in grain-orientedand non-grain-oriented sheet steel. Through the selection of rawmaterial and special technical treatments, it is possible to attenuatethe strong remnant magnetization without an external magnetic field andto convert the magnetic hysteresis into an R type. However, thepermeability of the material typically falls at the same time. A furtherpossibility arises by inserting an air gap into the magnetic core. Theparallel orientation of the magnetic domains in the remnant state isbroken at this air gap. Physics require the potential energy in thequasi-static system to be minimized and therefore prohibit an externalmagnetic field in the air gap for highly permeable magnetic sheet steel.Therefore, closing domains with a vertical magnetization direction formalong the edge to the air gap and in turn continue in the core throughdomains with an opposite magnetization direction, that is to say theparallel orientation of the magnetic polarization in one direction isprevented. The strong reduction in the permeability, which ispractically determined only by the ratio of the air gap width to theeffective magnetic core length, is also disadvantageous here.

However, a high permeability is needed to ensure the electronic tripreadiness for small primary currents in the case of a small availableinstallation space.

This is achieved, according to an embodiment of the invention, by way ofan energy converter having the technical values mentioned, which energyconverter consists of (modern) nanocrystalline material, for example,avoids the disadvantages mentioned and has the advantages mentioned.

Advantageous configurations are stated in the claims.

In one advantageous configuration of an embodiment of the invention, theenergy converter has a core, the saturation flux density of which is atleast 1 T, in particular at least 1.2 T. This has the particularadvantage that a high magnetic flux is achieved for a low magnetic fieldstrength, thus making it possible to achieve a small design for theenergy converter.

In one advantageous configuration of an embodiment of the invention, thecore of the energy converter is a nanocrystalline tape-wound core. Inparticular, tapes having a thickness of between 1 and 100 μm, morespecifically having a thickness of 10 to 35 μm, in particularthicknesses of 20 to 25 μm, are highly suitable.

This has the particular advantage that cores of virtually any desiredsize can be produced by placing the tapes on top of one another orwinding the tapes.

In one advantageous configuration of an embodiment of the invention, thecore has transverse magnetic anisotropy.

Transverse magnetic anisotropy is used to mean, in particular, magneticcross-field anisotropy.

This has the particular advantage that cores of this type, in particularmade of nanocrystalline tape, have virtually no remnant magnetic flux.The magnetic hysteresis has an F shape (flat), also see FIG. 2.Nevertheless, cores of this type have a permeability comparable toconventional magnetic sheet steel, in which case the magnetic power lossin the nanocrystalline toroidal tape-wound core is additionally verymuch lower.

In one advantageous configuration of an embodiment of the invention, thecircuit has at least one conductor which is guided through the circuitbreaker and the current of which is at least partially the primarycurrent of the energy converter.

This has the particular advantage that the complete current in thecircuit does not form the primary current of the energy converter orcurrent converter, but rather only a defined partial current. Thisenables a smaller design for the energy converter in the circuitbreaker.

In one advantageous configuration of an embodiment of the invention, theenergy converter is in the form of a ring or a toroidal core.

This has the particular advantage that it is possible to achieve aparticularly compact design for an energy converter since angular shapes(M section, E-I section, . . . ) have a greater space requirement forthe same power.

In one advantageous configuration of an embodiment of the invention, theenergy converter is arranged in a converter unit, also having a currentmeasuring device, for example a Rogowski coil.

This has the particular advantage that it is possible to form a compactcombination converter module for the self-supply and current sensorsystem of a circuit breaker.

All configurations, both in dependent form referring back to anindependent claim, and referring back only to individual features orcombinations of features of patent claims, improve a circuit breaker, inparticular the energy converter.

FIG. 1 shows a graph having a first magnetic hysteresis curve, forexample for a wound FeSi toroidal tape-wound core. The magnetic fieldstrength H in A/m (amperes per meter) is plotted on the horizontal Xaxis of the graph. The magnetic flux B in T (Tesla) is plotted on thevertical Y axis. A typical hysteresis, as is known to a person skilledin the art, is plotted. This type of curve is also referred to as aso-called Z shape. Important properties of the material depicted in thecurve are the magnetic saturation flux density Bs1, the remanence fluxdensity Br1, often also referred to only as remanence, and the coercivefield strength Hc1.

If a ferromagnetic core is wound with an electrical primary winding orprimary coil and a current is sent through the electrical conductor ofthe primary winding, the resulting magnetic field H [A/m] generates amagnetic flux B [T] in the core. The winding may also involve only oneturn or a conductor can be guided through a (toroidal) core, so-calledhalf the number of turns, in order to generate a magnetic flux in thecore.

This magnetic flux increases with increasing magnetic field orincreasing magnetic field strength. However, not arbitrarily, but ratheronly to the so-called saturation flux density Bs1. If the latter hasbeen reached, an increase in the magnetic field strength H does notincrease the magnetic flux B in the core. The flux remains constant atthe saturation flux density Bs1. This is indicated in FIG. 1 with therising arrow illustrated beside the right-hand part of thecharacteristic curve.

If the magnetic field H is only reduced to the value of zero again (H=0A/m), a magnetic flux Br1 nevertheless remains in the core. This isreferred to as the remanence flux density Br1.

The magnetic flux in the core can be changed to the value of zero again(B=0 T) only with a magnetic field directed in the opposite direction(negative magnetic field strength in FIG. 1). The magnetic fieldstrength Hc1 required for this purpose is referred to as the coercivefield strength Hc1. This is indicated in FIG. 1 with the falling arrowillustrated beside the left-hand part of the characteristic curve.

One aim of an embodiment of the invention is to reduce the state ofdelayed operational readiness of a circuit breaker as a result ofremnant magnetic flux Br1 in the core of the energy converter, withsimultaneously high permeability as far as possible and high magneticsaturation or saturation polarization, in order to achieve the smallestpossible size for the energy converter.

This is intended to be achieved, according to the invention, with ananocrystalline core as the energy converter.

Nanocrystalline tapes made of ferromagnetic materials are produced bythe rapid solidification of the melt on a rotating disk or roller toform an amorphous tape and defined thermal and magnetic post-treatmentof the wound amorphous tape.

The thermal post-treatment of the tape (annealing process) results inrecrystallization in the tape. Nanocrystals with ferromagneticproperties are formed. If this recrystallization process is carried outunder an external magnetic field, the easy axis of the magnetization isoriented with the magnetic field direction during the formation of thenanocrystals. After the wound nanocrystalline tape has been cooled, aferromagnetic core with very high permeability and very narrow magnetichysteresis, that is to say very low magnetic power loss, is obtained.Magnetic cores and current converters of this type can be operated intothe MHz range.

The hysteresis curve of such a core is illustrated in FIG. 2. FIG. 2shows a graph according to FIG. 1 with the difference that a magnetichysteresis curve for e.g. a nanocrystalline toroidal tape-wound core, inparticular with transverse anisotropy, is illustrated. This isdistinguished by a much lower residual flux density Br2 and a much lowercoercive field strength Hc2.

The magnetic saturation flux density Bs2 is approximately as large asthat shown in FIG. 1.

The curve has a so-called F shape (F for flat).

The relatively high saturation polarization of 1.2 T (at least 1 T) andthe very high permeability are particularly advantageous for use asenergy converters for circuit breakers for supplying energy to a controlunit, that is to say as the magnetically coupled energy self-supply ofthe electronic trip unit in the circuit breaker. The low magnetic corelosses are advantageous, in particular in power supply systems whichhave substantial current harmonics, as are nowadays increasingly exposedto the circuit breakers, since grain-oriented magnetic sheet steel hasvery high magnetic power losses at high frequencies.

As described above, the magnetic orientation in the wound tape-woundcore is influenced by the magnetic field during the recrystallization.If the magnetic field is oriented in an annular manner around the centerpoint of the toroidal core, longitudinal magnetic anisotropy is producedin the nanocrystalline tape. Toroidal cores of this type have anextremely high permeability but also a highly pronounced Z shape of themagnetic hysteresis. Therefore, such cores exhibit a pronounced remnantmagnetic flux.

If, in contrast, the external magnetic field is oriented in ahomogeneously parallel manner with respect to the toroidal core axis,transverse magnetic anisotropy is produced during the recrystallization.Toroidal cores of this type made of nanocrystalline tape have virtuallyno remnant magnetic flux since the magnetic polarization of thenanocrystals is oriented perpendicular to the ring circumference withoutan external field. The magnetic hysteresis has an F shape, asillustrated in FIG. 2. Nevertheless, cores of this type have apermeability comparable to conventional magnetic sheet steel, but themagnetic power loss in the nanocrystalline toroidal tape-wound core isadditionally very much lower.

Nanocrystalline toroidal cores of this type can replace the woundtoroidal cores made of grain-oriented magnetic sheet steel in the caseof a comparable magnetic core cross section, which is advantageous, inparticular, for circuit breakers, in particular for compact or opencircuit breakers.

At least one embodiment of the invention makes it possible to implementa circuit breaker with a comparatively small energy converter which canalso be implemented in networks with harmonics and in the case of highprimary currents which exceed the defined currents, in which case thereis a reliable energy supply for a control unit.

The following advantages can be achieved with a toroidal core made ofnanocrystalline tape:

Very high permeability;

High magnetic saturation polarization;

=>considerably smaller installation space than in the case of toroidalcores made of ferrite material with the same apparent power;

=>suitability for typical network frequencies.

Similar size to cores made of magnetic sheet steel with the sameapparent power;

=>easy replacement in existing designs.

Very narrow magnetic hysteresis, that is to say low magnetic power loss;

=>suitability for high frequencies;

=>suitability for networks with substantial current harmonics.

Furthermore, the following advantages result from the magneticanisotropy which can be set during the recrystallization process:

Very low remnant magnetic flux as a result of transverse magneticanisotropy;

=>no remanence effect;

=>undelayed tripping readiness of a control unit, for example ETU, inthe circuit breaker irrespective of the “prior history” when previouslyswitching off/tripping the circuit breaker.

The core material may contain, in particular, the elements Fe, Si, B, Nbor/and Cu.

A core according to an embodiment of the invention is intended to have,in particular, a remanence flux density Br which is less than 30%, inparticular less than 20%, of the saturation flux density Bs. Thecoercive field strength Hc is intended to be less than 10 A/m, inparticular less than 5 m/A.

If the core is in the form of a toroidal core, it may have both aninhomogeneously distributed secondary winding, that is to say asecondary winding concentrated on individual core sections or portionsof the core, and a homogeneously distributed secondary winding. Theprimary winding may also only be in the form of a conductor which isguided through the toroidal core.

The toroidal core may ideally be closed and may not have an air gap.

The toroidal core may be annular, circular, oval, square, rectangularetc.

The energy converter according to an embodiment of the invention may beadvantageously part of a converter unit, as illustrated in FIGS. 3 to 5.

FIG. 3 shows a schematic cross section through a converter unit 1(combination current converter) for a circuit breaker (not shown) whichis supplied with electrical energy by the converter unit 1 and issupplied with a signal for current measurement.

The converter unit 1 has a housing 2 which has the shape of a pot and iscomposed of an electrically insulating plastic. A hollow (passage)cylinder 2 b (generally a passage channel 2 c) is formed on the housingbase 2 a, through which cylinder a current conductor (not shown) runs asthe primary conductor (primary winding) of the converter unit 1. Theplastic has, by way of example, an insulating capacity of approximately20-30 kV/mm here.

A (first) secondary winding 3 lies on the housing base 2 a and isarranged concentrically in relation to the hollow cylinder 2 b and iswound onto a non-magnetic toroidal core 4 (Rogowski converter formeasuring current). The secondary winding 3 is at least predominantlyembedded in an electrically insulating solid plastic compound 5. It goeswithout saying that the secondary winding 3 may also be a simpletoroidal coil that is wound around the toroidal core 4.

A flat spacer element 6 in the form of a perforated disk rests directlyon top of the secondary winding 3 by way of its lower flat side, so thatthe secondary winding 3 is at least partially covered in a radial manneras seen from above. There is no plastic compound 5 between the secondarywinding 3 and the spacer element 6. In FIG. 1, the secondary winding 3is completely covered in a radial manner as seen from above.

A further (second) secondary winding 7, which is wound onto a coreaccording to an embodiment of the invention, in the example a magnetictoroidal core 8, for example, according to an embodiment of theinvention, made of nanocrystalline material (e.g. ferromagnetic coreconverter for supplying energy), lies on the upper side of the spacerelement 6. The spacer element 6 clearly defines the distance between thetwo secondary windings 3, 7. In this case, the magnetic toroidal core 8is composed of soft magnetic material, such as nanocrystalline materialaccording to an embodiment of the invention or material with thetechnical values according to an embodiment of the invention. It goeswithout saying that the winding 7 may also be a simple toroidal coilthat is wound around the toroidal core 8.

The secondary winding 7 is completely embedded in electricallyinsulating loose particles 9 above the spacer element 6. In FIG. 1, thewinding 7 is also completely covered by particles 9 in the direction ofthe top; the cover or the particle layer 10 has a thickness D in thiscase. In principle, an embedding arrangement in the radial direction 11is already sufficient. The particles 9 that bear against one another areonly schematically illustrated (at the top right) in FIG. 1. In otherwords, the particles 9 here fill the region next to and the region (withthe thickness D) above the secondary winding 7.

The particles 9 are glass balls with a suitable diameter distribution(for example in the form of a Gaussian distribution in this case). As analternative, however, said particles may also be ceramic powders orceramic granules, in particular aluminum oxide (Al₂O₃) with an averageparticle size of 300 μm. Cured resin can also be pulverized, inprinciple.

In this case, the thickness D of the particle layer 10 amounts toseveral average particle diameters.

The region directly adjoining the particle layer 10 is encapsulated withan encapsulant 12. In this case, the encapsulant 12 bears firmly(intimately) against the inside of the housing wall 2 d and at leastalso against the particles 9 that lie at the top in the direction of thehousing opening.

However, starting from the top side of the particle layer 10, theparticles 9 in FIG. 3 are even embedded in the encapsulant 12 down to adepth T of several average particle diameters, wherein the depth T isless than the thickness D of the particle layer 10. The encapsulant 12thus bears against the particles 9 (all the way around) virtually downto a depth T, not only in each case against the top side of theparticles 9 that lie at the top (at the very top) in the direction ofthe housing opening.

FIG. 4 shows an alternative converter unit 1 in which the top side ofthe second secondary winding 7 is covered by a thin film 13 instead ofwith a particle layer 10. The particles 9 that lie at the top in thedirection of the housing opening and are further to the outside, as seenin the radial direction, and are therefore not covered by the film 13are approximately in a plane with the film 13 in FIG. 4. The encapsulant12 now bears firmly (intimately) against the top side of the film 13 andat least against the outer upper particles 9 since the film 13 does notreach the inside of the housing wall 2 d.

The particles 9 in a plane with the film 13 can likewise be embedded inthe encapsulant 12 over several average particle diameters, but withoutthe encapsulant 12 reaching the second secondary winding 7.

In FIG. 4, the particles 9 are embedded in the encapsulant 12 overseveral average particle diameters. The embedding limit is schematicallyindicated by the dashed line 14.

FIG. 5 shows a flat perforated disk element 15 which corresponds to thespacer element 6 and rests on the film 13 and at least partially coversthe secondary winding 7 in a radial manner. This perforated disk element15 holds down the secondary winding 7 during filling with the glassballs, that is to say substantially prevents the secondary winding 7from floating. Alternatively, the film 13 may also rest on the spacerelement 6.

The connection wires 16, 17 of the secondary windings 7, 3 are guidedthrough the encapsulant 12.

The method for producing the converter unit 1 according to FIG. 3 (andaccordingly FIGS. 4 and 5) comprises the following steps:

-   -   the secondary winding 3 is inserted into the housing 4,    -   the spacer element 6 is then pushed onto the secondary winding        3,    -   the plastic compound 5 is then filled in, wherein the top side        of the spacer element 6 remains free of plastic compound 5,    -   the secondary winding 7 is then inserted into the housing 4,        with the result that it comes to rest on the top side of the        spacer element 6,    -   the particles 9 are then filled in, with the result that the        secondary winding 7 is surrounded by the particles 9 in a radial        manner and above and is embedded in said particles, and    -   the housing 4 which is open at the top is then encapsulated with        the encapsulant 12, the flow properties of which ensure that the        encapsulant 12 enters the particle layer 10 only to a depth T of        several average particle diameters, in which case the        encapsulation is carried out by way of a vacuum encapsulation        system, in order to avoid air inclusions.

The converter unit which is provided for a circuit breaker and has theenergy converter according to an embodiment of the invention ischaracterized, in particular:

-   -   in that the particles (9) cover the top side of the second        secondary winding (7) with a particle layer (10), the        thickness (D) of which amounts to several average particle        diameters;    -   in that, starting from the top side of the particle layer (10),        the particles (9) are embedded in the encapsulant (12) to a        depth (T) of several average particle diameters, wherein the        depth (T) is less than the thickness (D) of the particle layer        (10);    -   in that the top side of the second secondary winding (7) is        covered by a film (13) and the encapsulant (12) bears a) against        the top side of the film (13) and b) against the particles (9)        which are to the side of the film (13) and are at the top in the        direction of the housing opening and are in a plane with the        film (13);    -   in that the particles (9) which are to the side of the film (13)        and are at the top in the direction of the housing opening and        are in a plane with the film (13) are embedded in the        encapsulant (12);    -   in that the embedding does not extend to the second secondary        winding (7);    -   in that the particles (9) are spherical;    -   in that the particles (9) are in the form of glass balls;    -   in that a second flat perforated disk element (15) bears against        the film (13) by way of a flat side and at least partially        covers the film.

Although the invention has been described and illustrated morespecifically in detail by way of the exemplary embodiment, the inventionis not restricted by the disclosed examples and other variations can bederived herefrom by a person skilled in the art without departing fromthe scope of protection of the invention.

1. A circuit breaker for interrupting an electrical circuit upon atleast one of current and current period limit values being exceeded,having comprising: an energy converter, connected on a primary side tothe electrical circuit and, connected on a secondary side, to provide anenergy supply for at least one control unit of the circuit breaker, theenergy converter including a core, a remanence flux density of the corebeing less than 30% of a saturation flux density of the core, whereinthe core includes a ferromagnetic nanocrystalline material.
 2. Thecircuit breaker of claim 1, wherein the energy converter the saturationflux density of the core is at least 1 T.
 3. The circuit breaker ofclaim
 1. wherein the remanence flux density of the core is less than 20%of the saturation flux density.
 4. The circuit breaker of claim 1,wherein coercive field strength of the core is less than 5 A/m.
 5. Thecircuit breaker of claim 1, wherein the core of the energy converter isa nanocrystalline tape-wound core.
 6. The circuit breaker of claim 1,the energy converter is in a form of a ring or a toroidal core.
 7. Thecircuit breaker of claim 1, wherein the energy converter is provided asa converter unit including an electrically insulating pot-shaped housingwhich includes, at a bottom, a housing base and a hollow cylinderarranged on the housing base and extending upward into an interior ofthe housing, a non-magnetic toroidal core, including a first secondarywinding resting on the housing base in a concentric manner with respectto the hollow cylinder and embedded in a solid compound, the energyconverter being in a form of a ring and including a second secondarywinding arranged above the non-magnetic toroidal core in a concentricmanner with respect to the hollow cylinder, and an electricallyinsulating solidified encapsulant, usable to close an opening of thehousing, the encapsulant (12), permanently connected to an inside of ahousing wall of the housing, resting against the housing wall, wherein afirst flat spacer element is arranged between the first secondarywinding and the second secondary winding, wherein one flat side of aspacer element rests directly against the first secondary winding andanother flat side rests directly against the second secondary winding,wherein electrically insulating particles fill the space between thesecond secondary winding and the housing wall, in a radial direction, atleast to a top side of the second secondary winding, and wherein theencapsulant extends at least to particles at a top with respect to thehousing opening. 8.-11. (canceled).
 12. The circuit breaker of claim 1,wherein the energy converter the saturation flux density of the core isat least 1.2 T.
 13. The circuit breaker of claim 2, wherein theremanence flux density of the core is less than 20% of the saturationflux density.
 14. The circuit breaker of claim 2, wherein coercive fieldstrength of the core is less than 5 A/m.
 15. The circuit breaker ofclaim 3, wherein coercive field strength of the core is less than 5 A/m.